1231, DME code. Alternator, brushes, regulator ect..?

[dirtyE-30]

i have a code 1231 (92 318i) that has left me stranded and trickle charging batteries as a means to get home. Based on the research I've done I'm assuming there is a problem in the charging system, though my charging warning lilght does not illuminate when opporating the vehicle. When running my head lights especially, the car will start to loose electrical components, (ABS light goes on, tac drops to nothing, headlights dim or disappear ect....) This is making me lean towards the brushes/alternator/corrotion but after cleaning all the terminals and even replacing the ground strap from negative to ground and alternator to ground, I've got the same symptoms.

Is there any possible cause of this condition that I have over looked? Has the relay it's self gone bad on anyone? I tapped twelve volts to the control side and sure eough heard it click closed but i'm not sure of the resistance specifications.

I'm new to this forum, not to cars. I LOVE e-30's!!!! New to them too though so any and all information is greatly appreciated!

[dnguyen1963]

Did you check the voltage regulator and brushes?

[modernist]

Check battery voltage with the car off and with the car running. Car off should be ~12.6 volts and running should be ~14 volts. A faulty DME relay would cause a no-start condition; you have a voltage problem. It could be a problem with the alternator itself, voltage regulator, a loose wiring connection, loose alternator belt, or a failing battery.

[RedTeam]

Check battery voltage with the car off and with the car running. Car off should be ~12.6 volts and running should be ~14 volts. A faulty DME relay would cause a no-start condition; you have a voltage problem. It could be a problem with the alternator itself, voltage regulator, a loose wiring connection, loose alternator belt, or a failing battery.

Do this, it's a quick and easy test. I had a similar alternator issue not too long ago, with all sorts of weird electrical stuff happening before the motor eventually stalled. If the battery reads lower while it's running, the alternator's your problem. Removing it is also really easy if you want to take it to a shop to get it tested (I think most places test alternators for free). They might be able to assess the damage.

[dirtyE-30]

Do this, it's a quick and easy test. I had a similar alternator issue not too long ago, with all sorts of weird electrical stuff happening before the motor eventually stalled. If the battery reads lower while it's running, the alternator's your problem. Removing it is also really easy if you want to take it to a shop to get it tested (I think most places test alternators for free). They might be able to assess the damage.

In California I don't think they do that anymore, bench testing the alternator that is, but the DVOM test seems extremely simple and straight forward. I don't think it's the voltage regulator because I slowly lose electrical components (abs, stereo, head lights dim, fan speed slows, cluster lights, stall) and from what I've read on the forum it seems that a bad regulator allows too much current into the system, making brighter the head lights ect.
I wish I could say for certain it's the indicator bulb but it comes on sometimes and not others. KOEO it doesn't come on except for 10% of the time.... maybe the bulb is just going out, opening the exciter circuit. When I get enough time i'll be sure to do these tests as I'd really like to drive my BMW again!
thanks for the responses

[modernist]

I don't think it's the voltage regulator because I slowly lose electrical components

When a voltage regulator fails, voltage is too high or too low. When the vr in my friend's 300 SEL failed, the alternator was barely putting out enough voltage to keep the battery charged, much less run any accessories.

[Seawolf]

What year is your car ?

You may have an internally fused ABS relay - if you're lucky...

[dirtyE-30]

1992 318i

When a voltage regulator fails, voltage is too high or too low. When the vr in my friend's 300 SEL failed, the alternator was barely putting out enough voltage to keep the battery charged, much less run any accessories.

Alright had a little time after work today and I put a battery in fresh off the trickle charger. cleaned all terminals and triple checked them. voltage of the disconnected battery was 12.7, engine idling voltage read 12.1-12.3, seemed to be climing slightly but not very much, I turned on the head lights and the voltage dropped down to the mid 11's, but then quickly back up to 12ish when I turned them off. I only had them on for a short amount of time and the vehicle was at idle speed for the entirety of this time.

Fused abs relay? So just pull the abs relay and bang, problem fixed? that sounds too good to be true. I pulled the cluster, shitty job, to find that my charge bulb was not burned out, even though it only worked intermittently, and this most recent time I fired the car up I didn't have the time to really wire the cluster in well enough to have a good idea of what indicator lights were on and which ones were not. but the voltage never reached 13, and it didn't ever run the head lights for an extended period of time. These symptoms may indicate either faulty brushes or faulty voltage regulator?

what should the resistance of the positive wire from alternator to battery be? and I forgot to mention that I have been running 500 watts rms total stereo work for quite some times

[dnguyen1963]

Dude, the voltage regulator is a fifteen min job. Your voltage should be around 14 V with the car running. You are running off the battery right now.

[modernist]

Yeah 12.x volts is way too low even at idle. Sounds like the battery is fine though. My money is on the voltage regulator as well. The ABS relay has nothing to do with battery/charging voltage.

[dirtyE-30]

thank you guys for the advice

Voltage regulator it is then, yeah I see how easily accessible it is, and hopefully when I remove it I can inspect it and come to find that all I need is the brushes, which run like 4 dollars a piece at o'rielly's. regardless it seems like a very simple job and hopefully i'll have it done by valentines day, thank you all for the advice, greatly appreciated!

Anyone know what the resistance of the positive cable that goes from the alternator to the battery should be? no more than x ohms? I think I remember doing mine and it was something like 3 ohms, which I wasn't thrilled about, but it does have some distance to travel and this was before I cleaned the terminals.

[modernist]

afaik should have continuity